(a) Field of the Invention
This invention generally relates to an idler support system for supporting the idlers used in tubular conveyor systems. More specifically, to a system for supporting the idlers of pipe forming and pipe keeping sections of tubular conveyors.
(b) Discussion of Known Art
Pipe or tube conveyors are relatively new in the history of the bulk handling industry. Much of the known technology was developed by Japan Pipe Conveyor Company (JPC) in the mid seventies. When first developed, the pipe conveyor's high investment cost was considered a major disadvantage. However, with today's environmentally concerned world, the conveyor' self sealing ability makes it a very environmentally friendly conveyor system. Furthermore, the flexibility of pipe conveyor systems has the ability to replace a complete system of conventional straight or curved conveyors of large radii with one single run of belt, combining straight and vertical or horizontal curved sections. The tubular conveyor's flexibility is due in large part to the system's ability to accommodate both vertical and horizontal curves of relatively small radii, a feature that eliminates the need for equal number of junction houses with their corresponding drive, take-up, and transfer chute arrangements.
In simplified form, pipe conveyors are belts which have been formed into tubular sections by a set of radially positioned rollers or idlers. Typically, the material to be conveyed is delivered to the belt at an end of the belt while the belt in unwrapped or open. Then, the belt is gradually rolled up by means of pipe forming idlers into a tubular shape with overlapping edges. By maintaining the overlap and/or seal on top of the circular cross section, the conveyor insures that the material is conveyed to the head terminal. Once the material reaches the opposite end of the conveyor, the belt is then unfolded into a flat belt configuration to navigate the conventional head, drive and take-up pulley assemblies. On its return route the empty belt is reshaped into the circular geometry, which is maintained all the way to the tail pulley terminal where the process of unfolding and pipe forming repeats itself. To ensure that the material from the conveyor does not spill, or so that the material being carried is not exposed to the environment, the belt is sufficiently overlapped at the edges to seal the entrenched material to be conveyed. Typically, a hexagonal shaped idler arrangement is used to maintain the tube or pipe shape of the conveyor. In many situations, both the carrying (top) and the return side (bottom) of the conveyor are formed into the pipe shape by means of idlers.
Generally, the pipe conveyor resembles the conventional belt conveyor in it's drive, belt tensioning (take-up) systems, and material transfers. These aforementioned elements are similar if not identical with those of the conventional belt conveyor's. However, on the carrying side of the conventional belt conveyors, there are usually three (3) idler rolls forcing the belt into a continuous trough by virtue of gravity. In a conventional belt conveyor, both the carrying and the return sides of the belt are supported by the same standard deck section. These deck sections include the legs and/or footings that are used to support the idlers. Thus, a typical deck section for a conventional belt will be capable of supporting the three carrying idlers and the one return idler that is typically used with conventional conveyor systems.
Pipe conveyors, on the other hand, are equipped with pipe forming and shape keeping idlers. These idlers support the belt in a generally radial manner. This radial support is typically carried out by six idler rolls supported in a generally hexagonal manner by support panels or "idler panels." Each idler panel is supported in an upright position by external structure, which is in turn supported over concrete footings or sleepers (railway ties). Idler panels, often referred to as "double panels," are typically made from a single rectangular flat plate with bent edges. The plate is divided into an upper compartment and a lower compartment, each compartment having a hole of a size which allows the tube or curled belt to pass. Some of these designs locate all six idler rolls on the same side of the panel, with each idler roll being placed in close proximity to the next idler roll, and forming the honeycomb shape discussed above. Other designs utilize somewhat longer idler rolls placed in an alternating fashion on opposite sides of the panel forming the hexagonal shape with a slight overlap of the internal adjacent corners of each idler roll.
Field experience with idler panels has revealed that there are several important, long felt, problems and limitations with the traditional idler panel design. Some of these problems include problems associated with the failure of these panels. Tubular conveyor systems are frequently use to load vessels in highly corrosive marine environments. These environments coupled with the stresses imposed on the idler panels lead to the rapid corrosion and failure of the idler panels. Repair to the panels are difficult due to the fact that, once the metal has corroded, the corroded sections must be removed and replaced with new sections of metal. Since the panels are constructed from single flat sheets the welding of reinforcement sections of metal is impractical due to warpage of the panel from the heat imposed by the welding operations. Moreover, the corrosion is likely to present itself as irregularly shaped regions, making it difficult to properly remove and replace the corroded sections. Replacement of the panels is also difficult, but this is perhaps the only practical solution. However, removal of the panels requires that the panel itself be split or that the conveyor belt be separated to allow insertion of the belt through the openings in the panels. Thus, it will be understood that any of these operations will be very time-consuming, and thus very costly in terms of production time.
From the above discussion it will be understood that the remains need for an easily serviceable idler support system for tubular conveyor systems.
It will be understood that the remains need for an idler support system, for tubular conveyor systems, which is inexpensive and which can be easily modified or tailored to suit the field conditions.
The remains a need for an inexpensive idler support system for tubular conveyors, the system being serviceable in a piecemeal fashion, eliminating the need to cut or destroy the panel for servicing the idler supports.
There remains a need for an idler support system which can be easily adjusted for allowing the user to accommodate variations in the field and accommodate various idlers and belt configurations.
There remains a need for an idler support system allows adjustment of the support to the belt, or addition of idler panel locations to adjust for additional loads created by the curvature of the belt in installations where the belt rounds a corner, for example.
There remains a need for an idler support system which allows the addition of idler panel locations after the conveyor system has been installed, without requiring the need to destroy the panel by splitting the panel or add footings or ground anchored supports.
Still further, there remains a need for an idler support system for tubular conveyors which can be tailored for including a desired number of conveyor idler supports locations or locations for idler panels on the carrier side of the belt, while reducing the number of idler support locations or idler panels on the return side of the belt.
There remains a need for an idler support panel which can be installed without the needs to modify the panel in the field, and thus eliminating the need to split the panel vertically into half panels for replacement panel application.
Thus there remains a need for a system that eliminates the need to split the panel or the belt, and thus there remains a need for an idler panel system which eliminated the need for panel splicing hardware for replacement applications.
Additionally, there remains a need for an idler support system, for tubular conveyors, which is light in weight, and thus reduces shipping and handling costs.
Still further, there remains a need for a light weight support structure for tubular conveyors; the light weight of the support system allowing a corresponding reduction in the size of the support structure needed for the assembled conveyor system.